A video signal of an image aired by usual TV broadcast is corrected so as to match the current-luminance characteristic of a cathode ray tube (CRT). Therefore, for displaying such a video signal on a display device other than a cathode ray tube, a gray scale correction needs to be performed such that the video signal matches the driving voltage-luminance characteristic of the display device. As a result of such a gray scale correction, the video signal originally generated is matched to the characteristic of the display device, and thus an original image can be reproduced accurately. In the case of a color display, such a gray scale correction is performed independently for each of the three primary colors. Thus, the color temperature, white balance and the like are adjusted, so that the hue of the original image can be reproduced with high fidelity.
Typically, the gray scale correction of each color (correction of gamma characteristic) is performed by a cut and try method. According to the cut and try method, the gray scale of each pixel is corrected (fine-tuned), and then the luminance and the chromaticity of a color display pixel are measured. Such a gray scale correction and such a measurement are performed repeatedly until the luminance and the chromaticity of the color display pixel exhibit desired values.
In a conventional, generally used display device, one color display pixel is formed of three pixels for displaying the three primary colors of light, namely, red, green and blue. Recently, a display device having a color display pixel including four or more pixels for displaying different colors has been proposed. Such a display device is also called a “multiple primary color display device”. In a typical multiple primary color display device, the three colors of red, green and blue and also a different color are used, so that display can be provided with a wider color reproduction range (see, for example, Patent Document 1).
Patent Document 1 describes a display device including RGB three primary color light emitting cells and also light emitting cells (Gb, Bb) for emitting light of colors outside the triangle of the chromaticity diagram of the RGB light emitting cells. For displaying a color in the range of the chromaticity diagram of the RGB light emitting cells, the display device described in Patent Document 1 lights up only the RGB light emitting cells without lighting up the light emitting cells (Gb, Bb), which are other than the RGB light emitting cells. By contrast, for displaying a color outside the range of the chromaticity diagram of the RGB light emitting cells, the light emitting cells (Gb, Bb) are lit up. In this manner, increase in the power consumption is suppressed.